Commercial passenger transport aircraft are typically equipped with passenger seat row arrangements including different seats and different seat spacings or pitches corresponding to the class division of the passenger cabin(s), for example in first class, business class, and tourist or economy class. The seat spacing or pitch in the respective class is typically a significant criterium for the total number of passengers that can be transported in a given aircraft. With a smaller seat pitch, a larger number of seat rows can be installed, and the maximum possible number of seat places can be increased.
On the other hand, various regulations prescribe a relatively large or wide spacing distance between neighboring seat rows adjacent to emergency exits or normal-use exits of the transport aircraft, in order to form a crosswise or transverse aisle (i.e. an aisle extending crosswise or transversely relative to the longitudinal axis of the aircraft) leading to the respective exit. The prescribed minimum width of this transverse access aisle leading to an emergency exit depends on the aircraft type, as well as the geometry and the evacuation capacity of the respective emergency exit. For example, in the case of a double exit, the minimum width of the transverse aisle is 36 inches, while the minimum width of the transverse aisle accessing a single emergency exit is 20 inches.
A sufficient width of the transverse aisle is absolutely necessary in order to enable a rapid and trouble-free flow of passengers to the emergency exit in the case of an emergency evacuation. In this regard, an emergency evacuation of a commercial passenger transport aircraft is to be carried out within 90 seconds. A transverse aisle that is too narrow makes it difficult for passengers to recognize the emergency exit path between the successive seat rows, and also makes accessing the exit more difficult. Especially in the case of an emergency evacuation, the passengers must be able to easily and rapidly access the emergency exit with sufficient passage space and without any obstacles or hindrances.